Monodisperse spherical toner particles containing aliphatic amides or aliphatic acids

Abstract

A nonconductive toner composition comprising monodisperse spherical particles includes a binder polymer, a charge control agent, and an aliphatic acid or aliphatic amide uniformly distributed in the particles and present in an amount of 2.5 to 30% by weight of the toner composition. A method of forming a toner particle composition comprises the steps of: milling an aliphatic amide or an aliphatic acid in the presence of a binder polymer and a water-immiscible organic binder solvent to form a concentrate wherein the particle size of the aliphatic amide or aliphatic acid is less than one micrometer; dissolving a binder polymer and a charge control agent in a water-immiscible organic binder solvent to form a binder solution; mixing the aliphatic amide or aliphatic acid concentrate with the binder solution to form an aliphatic amide- or aliphatic acid-binder polymer dispersion; dispersing the aliphatic amide- or aliphatic acid-binder polymer dispersion in water containing a colloidal stabilizer to form an aqueous suspension of droplets; subjecting the droplets to shearing action to reduce droplet size and form limited coalescence particles; removing the water-immiscible organic binder solvent from the limited coalescence particles to form toner particles in an aqueous medium; and drying the toner particles.

What is claimed is: 
     
       1. A method for forming a toner particle composition, said process comprising the steps of: a) milling an aliphatic amide or an aliphatic acid in the presence of a binder polymer and a water immiscible organic binder solvent, thereby forming an aliphatic amide or aliphatic acid concentrate, said aliphatic amide or aliphatic acid having a particle size of less than one micrometer;   b) dissolving a binder polymer and a charge control agent in a water immiscible organic binder solvent, thereby forming a binder solution;   c) mixing said aliphatic amide or aliphatic acid concentrate with said binder solution, thereby forming an aliphatic amide- or aliphatic acid-binder polymer dispersion;   d) dispersing said aliphatic amide- or aliphatic acid-binder polymer dispersion in water containing a colloidal stabilizer, thereby forming an aqueous suspension of droplets;   e) subjecting said aqueous suspension of droplets to a shearing action, thereby reducing the size of the droplets and forming limited coalescence particles;   f) removing the water immiscible organic binder solvent from the limited coalescence particles, thereby forming toner particles in an aqueous medium; and   g) drying the toner particles.   
     
     
       2. A method according to claim 1 wherein said milling step is carried out in a media mill. 
     
     
       3. A method according to claim 1 wherein said toner composition comprises 2.5 to 30% by weight of said aliphatic amide or aliphatic acid. 
     
     
       4. A method according to claim 3 wherein said toner composition comprises about 5 to 10% by weight of said aliphatic amide or said aliphatic acid. 
     
     
       5. A method according to claim 3 wherein said aliphatic amide is the compound stearamide. 
     
     
       6. A method according to claim 1 wherein said binder polymer is a styrene polymer of from 40 to 100 percent by weight of a styrene monomer and from 0 to 45 percent by weight of one or more alkyl acrylate monomers or alkyl methacrylate monomers. 
     
     
       7. A method according to claim 6 wherein said styrene monomer is selected from the group consisting of styrene and vinyltoluene, and said alkyl acrylate or methacrylate monomer is selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, and mixtures thereof. 
     
     
       8. A method according to claim 1 wherein said binder polymer comprises: a copolymer of (a) at least one vinyl aromatic monomer; and (b) at least one second monomer selected from the group consisting of a conjugated diene monomer and an acrylate monomer selected from the group consisting of alkyl acrylate monomers and alkyl methacrylate monomers.